1. Field of the Invention
This invention relates to a control technique for the injection of fluids into a subterranean formation to increase the production of hydrocarbons during a secondary or tertiary oil recovery process. During a secondary or tertiary oil recovery process, many injection wells are controlled by monitoring the surface pressure, and then maintaining said pressure below the parting, i.e., fracturing, pressure of the formation receiving the injected fluids. However, many injection wells do not exhibit a discernible surface pressure, and thus cannot be controlled in this manner. Other injection controllers have maintained a constant mass flow rate of fluid into the subterranean formation regardless of the pressure variations occurring during fluid injection. U.S. Pat. No. 3,455,382 entitled "Injection Flow Control Apparatus for Wells", and issued to D. V. Chenoweth on July 15, 1969, describes an injection well controller of this type.
None of the previous control techniques teach measuring the pressure at the face of the zone receiving the fluid during injection while using such measured pressures to maintain the bottomhole pressure relatively constant during the injection of said fluids.